Prove that `(1+"cos"(pi)/(8))(1+"cos"(3pi)/(8))(1+"cos"(5pi)/(8))(1+"cos"(7pi)/(8))=(1)/(8)` .

Find the value "cos"(pi)/(11)+"cos"(3pi)/(11)+"cos"(5pi)/(11)+"cos"(7pi)/(11)+"cos"(9pi)/(11)

Prove that cos ^(4) (pi)/(8)+cos ^(4) (3 pi)/(8)+cos ^(4) (5 pi)/(8)+cos ^(4) (7 pi)/(8)=(3)/(2)

Prove that 2cos(pi/13)cos((9pi)/13)+cos((3pi)/13)+cos((5pi)/13)=0

One of the value of ("cos"(pi)/(6) +i "sin"(pi)/(6))^((1)/(2)) + ("cos"(pi)/(6)- i "sin"(pi)/(6))^((11)/(2)) is

Evaluate cos^2(pi/8)+cos^2((3pi)/8)+cos^2((5pi)/8)+cos^2((7pi)/8)=2

Find the value of "cos"^(2)(pi)/(16)+"cos"^(2)(3pi)/(16)+"cos"^(2)(5pi)/(16)+"cos"^(2)(7pi)/(16) .

Evaluate cos^2(pi/8)+cos^2((3pi)/8)

The principal argument of the complex number z = (1+ sin""(pi)/(3) + icos""(pi)/(3))/(1+sin""(pi)/(3) - i cos ""(pi)/(3)) is

Prove that cos((3pi)/4+x)-cos((3pi)/4-x)= -sqrt2 sinx

Prove that (cos(pi+x)cos(-x))/(sin(pi-x)cos(pi/2+x) = cot^2x